Machine and method for forming laminations for magnetic cores



A. F. MITTERMAIER 3,251,208

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES May 17,1966 '7 Sheets-Sheet 1 Filed May 27, 1963 INVENTOIR. Arm/1'2F/W/ZZ'erma/n b zzmy W May 17, 1966 A. F. MITTERMAIER 3 MACHINE ANDMETHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES 7 Sheets-Sheet 2 FiledMay 2'7, 1963 'IIIIIII/d my a.

F E R? Mu mm. m e A m May 17, 1966 A. F. MITTERMAIER 3,251,208

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES Filed May27, 1963 7 Sheets-Sheet s INVENTOR. firm/1'7 F/WZWEr/Wa/n May 17, 1966A. F. MITTERMAIER 7 ,2 8

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES 7Sheets-Sheet 4 Filed May 27, 1963 [n Manta)" Arm/h F/V/Z'Jer y 1966 A.F. MITTERMAIER 3,251,208

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES Filed May27, 1963 7 Sheets-Sheet 5 y 1966 A. F. MITTERMAIER 3,251,208-

MACHINE AND METHOD FOR FORMING LAMINATIONS FOR MAGNETIC CORES Filed May27, 1963 '7 Sheets-Sheet 6 AZ: tarwey.

May 17, 1966 A. F. MITTERMAIER 3,251,203

MACHINE AND METHOD FOR FORMING LAMINATIQNS FOR MAGNETIC CORES Filed May27, 1963 7 Sheets-Sheet 7 mg. as.

INVENTOR Arm/h Fi'Mimerma/kn by 71LHZ/ M d'zt'ormfg.

United States Patent 07 3,251,208 MACHINE AND METHOD FGR FORMING LAMI-NATIUNS FOR MAGNETIC (IORES Armin F. Mittermaier, Fort Wayne, Ind,assignor to General Electric Company, a corporation of New York FiledMay 27, 1963, Ser. No. 283,299 10 Claims. (Cl. 72-46) This inventionrelates to machines and methods for forming laminations for magneticcores. More particularly, it relates to such machines and methodsadapted for use in connection with magnetic cores comprised oflaminations preformed of strip steel so that the flux path isessentially in the direction of rolling of the strip steel.

In a conventional shell type of core, such as is widely used in smallpower transformers, the core is made by stamping lamination punchingsfrom strip steel and stacking the lamination punchings to form the corestructure. In the transverse portions of the core structure, the fluxtraverses a path that is essentially at right angles to the direction inwhich the strip steel was rolled. Magnetic cores formed of magneticmaterial, such as cold rolled silicon strip steel, are characterized bylower exciting current and core losses when the flux path is in thedirection of rolling. Thus, core structures made from laminationpunchings do not best utilize the properties of the cold rolled stripsteel.

In order to best utilize the directional characteristics of the magneticstrip steel, various methods have been proposed for forming thelaminations of magnetic cores. A core may be formed by providing one ortwo generally U-shaped core members of curved or bent strips of magneticmaterial and joining the U-shaped member at the ends to form a closedmagnetic circuit. Such U-shaped core members in the past have beenformed by bending a stack of pre-cut strips of magnetic material on amandrel to form a U-shaped configuration. Where two such U-shaped coremembers are to be joined to form a closed loop, heretofore difficultieshave been encountered in joining the ends of U-shaped core memberstogether as a unit. Further, in bending the stacks of pre-cut strips ofmagnetic material to form the desired U-shaped configuration themagnetic material is frequently bent beyond its elastic limit. Suchbending, of course, destroys or has a detrimental effect on the magneticproperties of the steel. Methods of making magnetic cores by preforminglaminations to predetermined sizes have also posed problems since thethickness of magnetic strip steel varies.

Because of this variation in thickness, the dimensions of individuallamination sections which are to be preformed cannot be predeterminedwith any degree of accuracy.

There has been a long standing need for a machine and method forpreforming laminations from a continuous strip of magnetic material.Further, it is extremely desirable that such a machine and method bereadily adaptable to automated and semi-automated manufacturingtechniques. It is also desirable when required that the laminations beassembled with a predetermined space factor and with staggered corejoints in order to minimize the core joint losses.

Accordingly, it is a general object of the present invention to providean improved method and machine for forming a magnetic core of anelectromagnetic induction apparatus.

Another object of the invention is to provide an improved machine formaking preformed laminations for a magnetic core wherein the directionalproperties of the strip steel used to form the laminations are moreeffectively utilized.

It is still a further object of the present invention to provide animproved method and machine for forming 3,251,203 Patented May 17, I966U-shaped laminations of a magnetic core wherein variations in thethickness of the magnetic strip material used are compensated for informing the individual laminations.

A more specific object of the present invention is to provide a methodfor making preformed laminations for a magnetic core that is readilyadapted to automated and semiautomated manufacturing techniques.

It is still a further object of the invention to provide an improvedmethod of forming magnetic cores having generally U-shaped laminationsin which the joints in the legs can be readily assembled anddisassembled to mount one or more coil assemblies thereon.

in accordance with one form of my invention, I have provided an improvedmachine for making lamination sections from strip material for preformedmagnetic cores comprised of lamination layers, each layer being formedof a pair of essentially U-shaped lamination sections. The improvedmachine for making lamination sections for such preformed magnetic coresincludes a strip length indexing means for indexing a first, second andthird length of strip material to form the first leg portion, the crossmember and second leg portion, respectively, of a U-shaped laminationsection. Further, in accordance with the present invention I haveprovided a means for adjustably varying the indexed lengths byincrements proportional to the thickness of the strip material asdetermined by a strip thickness gauging means thereby to provide theindexed lengths for a lamination section of a succeeding laminationlayer. The first and third lengths of the lamination section of asucceeding layer differ from the first and third lengths of thelamination sections of a preceding lamination layer by an incrementequal essentially to one thickness and the space factor, if included.The second indexed length or the length of the cross member of theU-shaped lamination section of the succeeding layer differs from thesecond indexed length of the preceding lamination layer by essentiallytwo increments.

The machine includes a forming means for bending the strip material toform the cross member and leg portions of the lamination sections and ameans for shearing the strip material at the third indexed length to cutoff the U- shaped lamination section from the strip material.Preferably, in the improved machine the indexing means is provided witha cylindrical cam arrangement having first, second and thirdcam surfacesfor indexing the first, second and third lengths of the laminationsections. The cam surfaces are adjustably rotatable to change the firstand third indexed lengths of a lamination section by one increment andto change the second indexed length by essentially twice the increment.Thus, in the improved machine the lamination sections formed for asucceeding layer are varied by increments proportional to the actualthickness of the strip material. An important advantage of thisarrangement is that the dimensions of the individual lamination sectionsare proportionally adjusted as the thickness of the strip materialvaries thereby making it possible to readily fabricate the laminationsections for preformed cores, irrespective of variations in thethickness of the strip material.

According to another aspect of the invention I have provided an improvedmethod for making the lamination sections of a preformed magnetic core.in carrying out the method of the invention, the lamination sections foran initial lamination layer are formed to provide substantially U-shapedlamination sections having a first and a second leg portion bent atsubstantially right angles with a cross member. The actual thickness ofthe strip material is determined before the succeeding lamination layeris formed, and the lamination sections for the succeeding layer areformed with leg portions having lengths that vary from the lengths ofthe leg portions of the lamination sections of the preceding layer byessentially one increment proportional to the actual thickness. Thecross member of the lamination section for the succeeding section isformed with a length that varies from the length of the cross member ofthe lamination sections of the preceding layer by essentially twoincrements.

The subject matter which I regard as my invention is set forth in theappended claims. The invention itself, however, together with furtherobjects and advantages thereof may be better understood by the followingdescription taken in conjunction, with the accompanying drawings inwhich:

FIGURE 1 is a perspective view illustrating how a group of laminationsections formed in accordance with the improved method and machine ofthe invention are assembled;

FIGURE 2 is a perspective view of a preformed magnetic core formed ofthe lamination sections fabricated in accordance with one form of theinvention;

FIGURE 2a is a fragmentary view of the joint of the core shown in FIGURE2 and partially disassembled to show one of the joining laminations;

FIGURE 3 is a diagrammatic sketch of the principal elements of theimproved machine shown in simplified form illustrating how the firstlength of the first leg portion of a lamination section is indexed;

FIGURE 4 is a view corresponding to the one shown in FIGURE 3illustrating how the forming operation is carried out to form the firstleg portion of a lamination section;

FIGURE 5 is another view corresponding to the view shown in FIGURE 3wherein the second length or the length of the cross member of aU-shaped lamination section is indexed in accordance with the invention;

FIGURE 6 is another view corresponding to one shown in FIGURE 3 whereina second forming operation is carried out to form the cross member ofthe U-shaped lamination;

FIGURE 7 is still another view corresponding to the view shown in FIGURE3 in which the third length or the length of the second leg portion of alamination section is indexed in accordance with the invention;

FIGURE 8 is a View corresponding to the one shown in FIGURE 3 whereinthe lamination section formed in accordance with the invention is cutoff from the strip material;

FIGURE 9 is a perspective view showing the overall arrangement of amachine embodying one form of my invention;

FIGURE 10 is a sectional view taken along line A-A of the view shown inFIGURE 9 with portions of the frame member broken away to illustrate theoperating parts thereof;

FIGURE 11 is a view taken along the section line BB as shown in FIGURE10 to illustrate the strip gauging member arrangement;

FIGURE 12 is a perspective view of one end of the machine shown inFIGURE 9 and illustrating the strip length indexing assembly, thethickness compensating assembly and the strip gauging member;

FIGURE 13 is a fragmentary view partly in section of the strip materiallocking means;

FIGURE 14 is a sectionalized view of the indexing unit;

FIGURE 15 is a fragmentary view in perspective of the cam follower; and

FIGURE 16 is a sectional view taken along line C-C of FIGURE 9illustrating the details of forming brake assembly and shearingmechanism used in the illustrative embodiment of the invention, thepneumatic system used to actuate the shearing blade being illustrateddiagrammatically.

Referring now to FIGURES 1 and 2a, I have illustrated therein severalpreformed lamination sections 10, 11, 12,

cal

13, 14, 15, 16 and 17 and in FIGURE 2 a magnetic core 19 made inaccordance with the present invention. As will be seen in FIGURE 2 themagnetic core 19 is comprised of a plurality of essentially U-shapedlamination sections formed from strip material by indexing, bending andshearing operations to provide a core wherein the flux will traverse apath that is always in the direction of cold rolling. The magnetic core19 is formed of two parts which are joined as shown in FIGURE 2a, topermit a coil or coils (not shown) to be assembled on the core 19. Inthe illustrated embodiment of the invention the laminations were formedwith long and short leg portions so that the joints between pairs of thelamination sections are staggered. 1

As is shown in FIGURE 1, a magnetic core of the type to which myinvention relates is formed of lamination layers 20, 21, 22, 23 each ofthe lamination layers including a pair of identical lamination sections.The innermost layer 29 includes the lamination sections 10, 11. Thedimensions of the lamination sections 12, 13, which form the next orsuccessive layer 21, are increased so that they can be superposed on thelamination sections 10, 11. In order to stagger the butt joints betweenlamination sections, pairs of the lamination layers are alternatelyreversed. Although in the exemplification of the invention no air gapswere included in the core, if required, air gaps may be readily providedby shortening the lamination legs by a predetermined amount, as will behereinafter more fully explained in connection with the detaileddescription of the machine used to form the lamination sections.

Having reference to the schematic diagrams in the FIGURES 3-8, whichillustrate the sequence of operations performed, I will now moreparticularly describe how the indexing, forming and shearing operationsare carried out. In the simplified form of the core making machineembodying the invention, as is shown diagrammatically in FIGURES 38, themachine generally comprises a forming brake assembly 25, a shearingmechanism 26, a strip length indexing assembly 27, a strip thicknessgauging member 28 and a thickness compensating assembly 29. The stripmaterial 30 is fed from a reel (not shown) located to the right of thethickness gauging member 28.

The shearing mechanism 26 is represented schematically by a shearingblade 49, and as will hereinafter be more fully described, the shearingblade 49 is pneumatically actuated to cut off the lamination sectionafter the indexing and forming operations have been completed. Theforming brake assembly 25 is actuated by switching a pivotally supportedforming brake 55 through essentially a degree angle to form a rightangle bend in the strip material 30. It will be appreciated that theforming brake 55 may be swung through an angle slightly greater than 90degrees in order to form lamination leg portions that will, whenassembled, more or less clamp together.

In general, the strip length indexing assembly 27, as showndiagrammatically, includes a cam follower unit 31 and the cam cylinders32, 33, 34 formed with cam surfaces 35, 36 and 37, respectively. Thethree lengths for a lamination section are indexed by moving aretractable follower 38 to a position of engagement against the camsurfaces 35, 36 and 37. It will be understood, of course, that the camfollower unit 31 is fixedly clamped against the strip material 30 sothat when the unit 31 is moved to a position of engagement with one ofthe cam surfaces 35, 36, 37 the desired length of material is indexedand supplied to the forming brake assembly 25.

The strip thickness gauging member 28 includes a blade 39 which can bebrought into engagement with the strip material 30 to gauge thethickness. It will be seen that the blade 39 is carried on one end of apivotally supported rocker arm 46. The other end of the rocker arm 4t)serves as a movable stop for the lever arm 41. As the thickness of thestrip material varies, the position of the movable stop will beproportionally varied. The thickness compensating assembly 29 cooperateswith the strip thickness gauging member 28 and the strip length indexingassembly 27 to impart an angular rotation to the cam cylinder 32, 33,34. This angular rotation is proportional to the actual thickness of thestrip material 30 as it is fed into the machine. Thus, the lever arm 41of the thickness compensating assembly 29 when moved from its positionof contact with the movable end of the rocker arm 40 to a position ofcontact with a fixed stop 42 will impart an angular displacement to thecam cylinders 32, 33, 34 that is proportional to the actual thickness ofthe strip material 30.

In the illustrated embodiment of the invention the strip gauging member28 and the thickness compensating assembly 29 come into play only aftera set of lamination sections for a given lamination layer are completed.When a lamination layer is completed, the lever arm 41 is engaged withthe shaft 43 in order to impart the desired rotation to the camcylinders 32, 33, 34. The cam surfaces 35, 36, 37 are designed to causethe first and second indexed lengths to be increased by one incrementproportional to the actual thickness and to cause the second indexedlength to be increased by twice the increment. Although in theexemplification of the invention, I have started to build up themagnetic core by first forming the innermost U-shaped laminationsections, it will be appreciated that the reverse procedure may befollowed, and the core be built up by first starting with the largest oroutermost lamination sections.

In accordance with the present invention, successive lamination sectionsare progressively built up by varying the indexed lengths by incrementsproportional to the actual thickness as determined by the strip gaugingelement 28. The dimensions of the first or the innermost U-shapedlamination section are fixed by positioning the cam cylinders 32, 33, 34so that when the indexing unit 31 is moved from a position where itbutts against the stop 44 to a position where the cam follower 38engages the cam surface 37, a sufiicient amount of strip material isindexed to form the first leg portion of the U-shaped laminationsection, as is shown in FIGURE 3. After the first length is indexed, theforming brake assembly 25 is actuated, and the strip material is bent toform the first leg portion 45. When the cam follower 33 is moved fromits position of engagement with the first cam surface 37 to the secondcam surface 36, the amount of material required for the cross member ofthe U-shaped lamination section is indexed as is shown in FIGURE 5. InFIGURE 6 I have shown the forming brake assembly 25 actuated to providea ninety degree bend in the strip material at the second indexed lengthto thereby form the cross member 46 of the lamination section.

Moving the cam follower 27 to a position of engagement with the thirdcam surface 35 causes a sufficient amount of strip material to be fedout for the second leg portion 47. The shearing mechanism 26 is nowactuated to cut off the lamination section as is shown in FiGURE 8.Thus, the first lamination section is completely formed. Since thecomplementary U-shaped lamination section in the same layer has the samedimensions, the angular setting of the cam cylinder is not changed toform this next lamination section.

It will be seen from FIGURE 8 that after the lamination section is cutoff, the left end of the strip material 30 is in line with the cuttingedge of the shearing blade 49. To repeat the operations, the indexinguntil 31 is released from its locking engagement with the strip material30 by turning the control knob 50. The indexing unit 31 is brought backto its starting position where it butts against the stop 44. When inthis position, the indexing unit 31 is locked into engagement with thestrip material 36 and is moved to the left until the cam followerengages the first cam surface 37 to index the length of the first legportion, as is shown in FIGURE 3. The opera- 6 tions shown in FIGURES4-8 are then repeated to form the second lamination section of the firstlayer.

After the first U-shaped lamination sections for the innermost layer ofthe core are formed, an angular rotation is imparted to the three camcylinders 32, 33, 34 by the lever arm 41 so that the three indexedlengths are increased by increments proportional to the actual thicknessas guaged by the strip thickness gauging element 28. It will beunderstood that when the indexing, forming and shearing operations arebeing carried out, the cam cylinders 32, 33 and 34 are locked inposition. In order to impart the desired angular rotation to the camcylinders 32, 33, 34 after a lamination layer is completed, the leverarm 41 is first released from its engagement with the shaft 43-.

It will be noted that a spring 51 biases the rocker arm 49 so that thegauging blade 39 is held in contact against the strip material. Also, aspring 52 maintains the lever arm 41 in contact with the end of therocker arm 40. Thus, when the lever arm 41 is released for rotation, arotation proportional to the thickness of the strip material is impartedto the lever arm 4-1. When rotated to this position, the rocker arm 41is locked into engagement with the shaft 43 and is rotated in acounterclockwise direction, as seen in the view of FIGURE 3 until itabuts against the stop 42. An angular rotation, that is proportional tothe distance between the end. of the rocker arm 41 and the stop 42, isimparted to the cam cylinders 32, 33, 34. Since the rocker arm 41increases and decreases this distance proportionally as the thickness ofthe stop material varies, the angular rotation is also proportional tothe actual thickness. The cam surfaces 35, 35 and 37 are designed sothat the angular rotation results in an increase in the first indexedlength (provided by cam surface 37) of one increment. This increment isequal to the actual thickness plus a space factor, which may be includedby adjusting the position of stop 42, as will hereinafter be more fullyexplained. Further, cam surface 36 is designed so that the angularrotation produces an increase in the second indexed length that is twicethe increment, and cam surface 35 is designed to vary the third indexedlength by one increment.

Preferably, after the angular adjustment of the cam cylinders 32, 33, 34has been made, the shaft 43 is locked in position, the lever arm 41 isreleased from its engagement with the shaft 43 and locked in an angularposition so that the gauging blade 39 is disengaged from its contactwith the stop material. The angular position of the cam cylinders 32,33, 34 is set for forming the lamination sections of a succeedinglamination layer, and the indexing, forming and shearing operationsillustrated in FIGURES 3-8 are carried out to make the laminationsections of the succeeding layer.

Having more specific reference to FIGURES 9-16, the machine disclosedherein by way of a specific exemplification of the invention will now bemore fully described. I have identified the parts in FIGURES 9-16, whichcorrespond to the parts illustrated diagrammatically in FIGURES 38, bythe same reference numerals. machine, as shown in FIGURE 9, is generallyidentified by the reference numeral 60 and is supported on a table 61 ata height. convenient for manual operation.

Referring now more particularly to FIGURE 9, it will be seen that thestrip material '30 is supplied from a roll 62 carried on a turntable 63.The turntable 63 is supported by a horizontally extending bracket 64attached to the table 61. When the roll 62 of strip material is placedon the turntable 63 and 'fed into the machine 60', the strip material 30is positioned so that the lower edge of the strip material 3i? in themachine 69 and the bottom side of the roll 62 will lie essentially inthe same horizontal plane. As the strip material 39 is unwound from theroll 62, the turntable d3 revolves to prevent any undue strain frombeing applied to the strip material 30 as it is drawn through themachine 6ft. Four adjustable ver- Thetical posts 65 are provided to keepthe strip material on the turntable 63 as it unreels.

The strip material 30 is maintained in an essentially vertical positionby a pair of lower guide plates 66 supported by the vertical framemembers 67 and 68. The upper guide plates 69 are provided toallowrelatively wider strip material to be handled by the machine 60. Avertical guide post 70 is provided at a point adjacent to where thestrip material 31) enters the strip thickness gauging member 28.

As is shown in the view of FIGURE 9, the handle 90 of the lever arm 40of the strip thickness compensating assembly is located at the rightside of the machine 60 where it can be conveniently operated. Thecontrol knob 92 is provided to lock and unlock the shaft 43 whichcarries the cam cylinders 32, 33 and 34 of the strip length indexingassembly 27. The shaft 43 is rotatably supported by the frame members 73and '74 and is rotatable when unlocked. The three cam cylinders 32, 33,34 are adjustably secured to the shaft 43 so that the axial position ofthe cylinders can be changed to accommodate various core designs. An arm76 is also mounted on the shaft 43 to provide a limit for the angularrotation of the shaft 43. When the arm '76 butts against the stop 77 anyfurther angular rotation of the cam cylinders 32, 33, 34 in onedirection is restrained. For the convenience of the operator in settingthe position of the cam cylinders 32,. 33, 34, a scale 84 is mounted ina horizontal position between the frame members 73 and 74.

For a given angular position of the cylinder 32, 33, 34, three lengthsof strip material are indexed when the indexing unit 31 is moved fromits initial position against the stop 44 and when cam follower 38 issuccessively brought into contact with the cam surfaces 37, 36 and 35.It will be seen that the indexing unit 31 is carried on a pair of rails78, 79. When the indexing unit 31 is locked inengagement with the stripmaterial 30, as it is moved the indexing unit 31 feeds the stripmaterial 30 to the forming brake assembly 25 in the desired indexedlengths. When the indexing unit 31 is moved from the stop 44 so that thecam follower 38 engages the first cam surface 37, the first length ofthe lamination section is indexed, and when it is moved to engage thesecond and third cam surfaces 36 and 35, the second and third lengths ofthe lamination section are indexed. The indexing unit 31 can bedisengaged from the strip material 30 by turning the control knob 50.

In the view shown in FIGURE 9 only the control handle 81 and the controlvalve 82 of the shearing mechanism are shown. When the control handle 81is in the position as shown, the shearing blade of the shearingmechanism, as will hereinafter be more fully explained in connectionwith FIGURE 16, is in the standby condition, and the shearing blade isactuated to its cutting position when the handle is actuated by theoperator who stands in fer more particularly to the views illustrated inFIGURES 10-16. As is shown in FIGURE 10, the gauging rocker arm 40 isrotatably supported by the brackets 86 and 87. The gauging blade 39 issufiiciently long to accommodate strip material of various widths. Inthe illustrated exemplification of the invention the rocker arm 40 wasproportioned so that a of an inch displacement of the gauging blade 39produced a of an inch displacement r of the contact member 38 attachedto the rocker arm 40. The spring 51 attached at one end to a bracket 89and at the other end to the rocker arm 40 biases the gauging blade 39into engagement with the strip material 30 when .the lever arm 41 isreleased for rotation and an angular 8 adjustment is to be made to thecam cyilnders 32, 33 and 34.

It will be appreciated that when the indexing, forming and shearingoperations are being carried out, the gauging blade 39 is normallydisengaged from contact with the strip material 30. This is accomplishedby rotating the lever arm 41 in a clockwise direction, as seen in FIG-URE 10, to force the rocker arm 40 to pivot and disengage the gaugingblade from the strip material 30. A spring 52 attached at one end to theframe member '74 and attached at the other end to the lever arm 41biases the lever arm 4-1 into engagement with the contact member 88 ofrocker arm 40. A handle 90 is attached to the lever arm 41 in order thatthe operator can conveniently move the lever arm 41 from a position ofcontact with the contact member 88 to the stop 42 or vice versa. A setscrew 91 controls the stop 42 to permit adjustments to be made in orderto provide a space factor for the assembled core if desired.

As will best be seen in FIGURE 11, the shaft 43 is locked in a givenangular position by the control knob 92. When control knob 92 is turnedin one direction it will be seen that a slug 93 is pressed against adisc 94 which is rigidly secured to the shaft 43. When the control knob92 is turned in a reverse direction, the slug 94 is released fromengagement with the disc 94, and the shaft 43 is free to rotate. Theother control knob 95 permits the lever arm 41 to be engaged anddisengaged from the disc 94. When the lever arm 41 is engaged or lockedagainst the disc 94 and the operator moves the handle 90, the shaft 43will rotate, and an angular rotation will be imparted to the camcylinders 32, 33, 34. When the lever arm 41 is disengaged from the disc94, it is free to rotate about the shaft 43. It will be understood thatwhen the indexing, forming and shearing operations are performed by theoperator, the control knob 92 is in the locked position. When the stripmaterial 30 is being indexed, the handle 90 of the lever arm 41 ispushed over in a clockwise direction, as seen in FIGURES 10 and 12, tocause the gauging blade 39 to be withdrawn from contact with the stripmaterial 36, and the control knob 95 is turned to lock the lever arm 41in this position.

Turning now more specifically to the strip length indexing assembly 27,as shown in FIGURES 12, 13, 14, this assembly will now be more fullydescribed. It will be seen that the cam cylinders 32, 33, 34 are securedfor rotation with the shaft 43 by a suitable means such as key 96. Itwill be noted that a portion of the cam surface 35 of the cam cylinder32, as will be seen in FIG- URE 12, overlies the cam cylinder 33. Asmall handle 98 is provided on the indexing unit 31 so that the unit 31can be moved by the operator along the rails 78 and 79.

The indexing unit 31 is locked into engagement with the strip material31) by turning the control knob 50.

As is shown in the fragmentary view of FIGURE 13, when control knob 50is turned in one direction the block 99 exerts a compressive forceagainst an angle-shaped element 160, which in turn is forced against thestrip material 30. The indexing unit 31 is thereby secured in engagementwith the strip material 30 so that as the indexing unit 31 is moved onthe rails 73 and 79, the strip material 30 is carried with the indexingunit 31. It will be seen that the angle-shaped element 1% positions thestrip material 36 and cooperates with the rod 97 of the adjustablepositioning member (shown in FIGURES 10 and 12) to maintain thehorizontal alignment of the strip material 31).

Referring now more particularly to the sectional view of the indexingunit 31 shown in FIGURE 14, it will be noted that the cam follower 38 isprovided at the upper end with aswivel 101 to cause the cam follower 38to be retracted to various positions. When the swivel 111-1 is in thehorizontal position as shown in FIGURE 14, the cam follower 33 willengage the first cam surface 37. The swivel 101 is rotated to a secondposition, the cam ation sections by a fixed amount.

follower 38 is retracted, and will engage the second cam surface 36. Ina third position the swivel 101 will cause the cam follower 38 to befurther retracted so that the cam follower 38, when moved by theoperator towards the forming brake assembly, will pass over the camsurface 36 and engage the cam surface 35.

In FIGURE I have illustrated a fragmentary view of the cam follower 38to illustrate the specific details of its construction. It will be seenthat a pair of V- shaped axially extending grooves 102 and 103 areformed on the cylindrical periphery of the cam follower 38.

A ball bearing 104 is normally biased into either of the grooves 102 or103 so that one of the contact points 106 or 107 may be used. The ballbearing 104 and the spring 105 function as a detent means to releasablyengage the cam follower 38 in one of two angular positions. It will benoted that the contact point 106 is at a shorter radial distance fromthe central axis of the cam follower 38 than contact point 107. Thepurpose of this arrangement is to make it conveniently possible for theoperator to vary the length of the leg portions of lamin- For example,where it is desired to form a bridged gap in the preformed magneticcore, the length of a leg portion of the lamination sections may beshortened so that when the lamination sections are assembled, theshorter leg portion will be spaced from the end of the laminationsection in the same lamination layer to define an air gap. Also, it willbe apparent that by varying the lengths of the legs staggered jointconfigurations can be achieved as may be desired in a particular coredesign.

Although I have shown only two contact points 106 and 107 on the camfollower 38, it will be understood, of course, that additional contactpoints and slots may be formed in the cam follower 38 as may be requiredfor forming the lamination sections of a specific core design.

Having more specific reference to FIGURE 16, I will more fully describethe component assemblies that carry out the forming and shearingoperations of the machine 60. It will be seen that the strip material30, as it is indexed, is fed out beyond the guide member 108 and alongthe forming brake shoe 55. The shoe 55 is pivotally carried by therotating support member 10 which allows the shoe 55 to pivot essentiallyabout a vertical axis and form bends in the strip material 30. Thus, thestrip material 30 is bent to a substantially right angle by swinging theshoe 55 to the position shown in dished outline where it butts againstthe stop screw 112. As was previously mentioned, the laminationssections may be formed with an inside angle that is slightly less than90 degrees so that the leg portions of successive lamination sectionswill engage the lamination sections on which they are superposed with aclamping action.

The shearing mechanism 26 is comprised of a crank shaft 113 which isjournaled in the bearings 114 and 115 carried by the frame members 140and 141. The shearing blade 49 is driven by the crankpin r116 actuatedby a lever 117 keyed to the crank shaft \113. The alignment of theshearing blade 49 is maintained by four .adjustably supported guideblocks 118, 119, 120 and 121. A hardened cutting blade insert 122 isattached to the shearing blade 49 to permit the insert 122 to be readilyremoved for servicing. As the lever arm 117 is raised or lowered, itwill be seen that as crank shaft 1113 rotates, the shearing blade 49 isdriven through the strip material 30, and a shearing action is effected.

As is shown diagrammatically in FIGURE 16, the lever arm 117 is actuatedby a pneumatic piston and cylinder assembly 123 which is mounted in ahousing 124 attached to a support plate 125. A pair of control lines 126and 127 are brought out to the control valve 82 mounted near the frontside of the machine. The control valve 82 is connected to a source ofcompressed air (not shown). When the control handle 81 is in the 10position shown in FIGURE 16, the air supplied to the piston and cylinderassembly 123 issuch that the shearing blade 49 is maintained in thewithdrawn position as shown. When the handle 81 is moved inwardly toactuate the control valve 82, the air flow to the piston and cylinderassembly 123 is reversed, and the lever 117 is raised to actuate theshearing blade 49.

In order to firmly position the strip material 30 so that the formingand shearing operations can be carried out without unduly straining,misaligning or distorting of the strip material 30, I have provided agripping element 130. The gripping element 130 swings in and out ofengagement with the strip material 30 and is carried on a pivotallysupported vertical shaft member 131. A spring 132 biases the grippingelement 130* away from the strip material 30. A shaft 133, which isattached to the handle 33 (shown in FIGURE 9) is formed with aneccentric portion 134. When handle 83 is turned, the eccentric portion134 forces the gripping element 130 against the strip material 30 andthereby securely clamps the strip material 30 so that the forming andshearing operations can be properly carried out.

From the foregoing description, it will be apparent that the presentinvention makes it possible to readily fabricate the lamination sectionsof preformed magnetic cores. Although in the illustrated exemplificationof my invention I have shown and described a core forming machinespecially adapted for manual operation, it will be appreciated that thebasic operations performed by the manual operation of the machine areadaptable to automated and semiautomated manufacturing techniques.Further, the particular embodiment of my invention, which I havedisclosed, clearly illustrates the principles of operation of theinvention, and as a result of this disclosure many modifications will beapparent to those skilled in the art. Accordingly, it is to beunderstood that I intend by the appended claims to cover all suchmodifications that fall within the true spirit and scope of theinvention.

What I claim as new and desired to secure by Letters Patent of theUnited States is:

1. In a machine for making laminations for magnetic cores withlamination layers formed of pairs of lamination sections, each of thelamination sections having a pair of leg portions and a cross memberjoining said leg portions, a strip material supply means, a stripthickness gauging means for measuring the actual strip thickness, astrip length indexing means for indexing a first, second and thirdlength of strip material, said first length forming one leg portion,said second length forming said cross member, and. said third lengthforming the other leg portion of a lamination section, means coupledwith said indexing means for adjustably varying the indexed lengths byan increment proportional to the actual strip thickness as determined bysaid gauging means to provide a first and a third indexed length forlamination sections of a succeeding lamination layer that differs fromthe first and third lengths of the lamination section of a precedinglamination layer essentially one increment proportional to the stripthickness, and to provide a second indexed length for laminationsections of the succeeding lamination layer that differs from the secondlength of the lamination section of a preceding lamination layer byessentially two increments thereby to progressively provide the indexedlengths for each successive layer by alteration of said lengths by saidrespective increments between the formation of each successivelamination layer, forming means for bending said strip material at saidfirst and second indexed lengths, and means for shearing said stripmaterial at the third indexed length to cut off said laminationsections.

2. In a machine set forth in claim 1 wherein said strip length indexingmeans includes a cylindrical cam means having a first, second and thirdcam surface for indexing said first, second and third lengths of alamination section, said cylindrical cam means being adjustablyrotatable to cause said first and third indexed lengths to be changed bysaid one increment and to cause said second indexed length to be changedby twice said increment.

3. In a machine for making laminations from strip material for magneticcores with lamination layers formed of a pair of preformed sections,each of the preformed lamination sections having at least a first andasecond leg portion, a strip material supply means, a strip thicknessgauging means for measuring the actual thickness of the strip material,a strip length indexing means for controllably feeding out a first and asecond indexed length of strip material to provide the material for thefirst leg portion and the second leg portion respectively of a preformedlamination section, means coupled with said indexing means foradjustably varying the first and second indexed lengths by incrementsproportional to the actual thickness as determined by said stripthickness gauging means to provide a first and second indexed length forlamination sections of a succeeding layer that differs from the firstand second indexed lengths of the lamination sections of a precedinglamination layer by at least one thickness thereby to progressivelyprovide the lengths for each successive layer by alteration of saidlengths by said respective increments between the formation of eachsuccessive lamination layer forming means for bending the strip materialto form the leg portions of the lamination section, and means forshearing the strip material at the second indexed length to cut off saidpreformed lamination section from said strip material.

4. In the machine set forth in claim 3 wherein said indexing meansincludes a cylindrical cam means having at least a first and second camsurface for indexing said first and second indexed lengths of alamination section, said cylindrical cam means being adjustablyrotatable to change said first and second indexed lengths by at leastone increment.

5. In a machine for making laminations from strip material for amagnetic core with lamination layers formed of pairs of laminationsections, each of the lamination sections having a first and a secondleg portion bent substantially at right angles to form a cross memberjoining the first and second leg portions, a strip material supplymeans, a strip thickness gauging means for determining the actualthickness of the strip material; a strip length indexing means forfeeding a first, a second and a third indexed length of strip materialto provide the strip material to form the first leg portion, the crossmember and the second leg portion respectively of a lamination section,means cooperating with said gauging means and said indexing means foradjustably changing the first and third indexed lengths in incrementsproportional to the actual thickness of the strip material as determinedby saidgauging means to provide a first and a third indexed length for alamination section of a succeeding lamination layer that differs byessentially one thickness from the first and third lengths of alamination section of a preceding lamination layer and to provide asecond indexed length for said succeeding lamination section thatdiffers by essentially two thicknesses from the second indexed length ofthe lamination section of the preceding lamination layer toprogressively provide the lengths for each successive layer. byalteration of said lengths by said respective increments between theformation of each successive lamination layer, forming means for bendingthe strip material at the first and second indexed lengths, and meansfor shean'ng said strip of material at the end of said third indexedlength to cut off said U-shaped lamination section from said stripmaterial.

6. In the machine set forth in claim 5 wherein said indexing meansincludes a cylindrical cam means having a first, second and third camsurface for indexing said first, second and third indexed lengths of alamination bending the strip material substantially at right angles,

a shearing means for cutting off the lamination sections from the stripmaterial, indexing means for feeding a first,

second and third indexed lengths of the strip material to the formingand shearing means, said indexing means including a cylindrical cammeans formed with a first, second and third cam surfaces for indexingsaid first, second and third indexed lengths of a lamination section, acam rotating arm operatively associated with said cylindrical cam toimpart an angular rotation thereto, a strip thickness gauging rocker armpivotally supported for engagement with the strip material at one endthereof and at the other end thereof for providing a stop for said camrotating arm, said cam arm when engaged with said stop thereby impartingan angular rotation to said cylindrical cam means proportional to theactual thickness of the strip material as determined by said rocker arm,and ,said angular rotation causing said first and third cam surfaces tochange the first and third indexed lengths of a lamination section by anincrement proportional to the actual thickness of the strip material andcausing said second cam surface to change the second indexed length bytwice said increment.

8. A machine for making laminations from a strip material for magneticcores comprised of lamination layers formed of at least a pair ofcomplementary lamination sections, said machine comprising: a stripsupply means, a forming means for bending the strip materialsubstantially at right angles, shearing means for cutting off thelamination sections, a strip length indexing means for feeding the stripmaterial in at least a first and second indexed length to said formingmeans and said shearing means, said strip length indexing meansincluding cam cylinders formed with cam surfaces for indexing said firstand second lengths of said lamination sections, said cam cylinders beingadjustably rotatable to change said indexed lengths by incrementsproportional to the thickness of the strip material, a strip thicknessgauging means for determining the actual thickness of the stripmaterial, and means cooperating with said strip length indexing meansand said strip gauging means for changing the indexed lengths of saidstrip material in increments proportional to the actual thickness asdetermined by said strip thickness gauging means.

9. In a machine for making laminations from strip material for amagnetic core comprised of lamination layers formed of pairs ofpreformed sections, a forming means for bending the strip material atsubstantially right angles, a shearing means for cutting off the formedlamination sections from the strip material, an indexing means forfeeding indexed lengths of the strip material to said forming and saidshearing means, said indexing means including cam cylinders formed withcam surfaces for indexing said lengths of said strip material, said camcylinders being adjustably rotatable to change said indexed lengths bysaid increments, gauging means for measuring the thickness of the stripmaterial before it is suppled to the forming and shearing means, andmeans coupled with said indexing means to vary said indexed lengths ofstrip material by increments proportional to the actual thickness of thestrip material as determined by said gauging means.

10. A machine for making laminations from strip material for magneticcores comprised of layers formed of pairs of U-shaped laminationsections said machine comprising: a strip supply means, a forming meansfor forming substantially right angle bends in the strip material, ashearing means for cutting off the lamination sections from the stripmaterial, indexing means for feeding a first, second and third indexedlengths of the strip material to said forming means and said shearingmeans, said indexing means including cylindrical cam means having afirst, second and third cam surface for indexing said first, second andthird indexed lengths, said cylindrical cam means being adjustablyrotatable to change said first and third indexed lengths by oneincrement and to change said second indexed length by twice saidincrement, a strip gauging means for determining the actual thickness ofthe strip material, and means coupled with said indexing means toadjustably change the first 14 to the actual thickness of the stripmaterial as determined by said gauging means and to change said secondindexed lengthby twice said increment.

References Cited by the Examiner UNITED STATES PATENTS 2,910,767 11/1959Loy 29155.61 3,031,003 4/1962 Clemons 153---2 3,096,568 7/1963 Biggs etal. 29155.6l 10 3,096,805 7/1963 Biggs et a1 1532 CHARLES W. LANHAM,Primary Examiner.

JOHN F. CAMPBELL, Examiner.

and third indexed lengths by one increment proportional 15 W- HURCH, R-D. GREFE, s ant Examiners.

1. IN A MACHINE FOR MAKING LAMINATIONS FOR MAGNETIC CORES WITHLAMINATION LAYERS FORMED OF PAIRS OF LAMINATION SECTIONS, EACH OF THELAMINATION SECTIONS HAVING A PAIR OF LEG PORTIONS AND A CROSS MEMBERJOINING SAID LEG PORTIONS, A STRIP MATERIAL SUPPLY MEANS, A STRIPTHICKNESS GAUGING MEANS FOR MEASURING THE ACTUAL STRIP THICKNESS, ASTRIP LENGTH INDEXING MEANS FOR INDEXING A FIRST, SECOND AND THIRDLENGTH OF STRIP MATERIAL, SAID FIRST LENGTH FORMING ONE LEG PORTION,SAID SECOND LENGTH FORMING SAID CROSS MEMBER, AND SAID THIRD LENGTHFORMING THE OTHER LEG PORTION OF A LAMINATION SECTION, MEANS COUPLEDWITH SAID INDEXING MEANS FOR ADJUSTABLY VARYING THE INDEXED LENGTHS BYAN INCREMENT PROPORTIONAL TO THE ACTUAL STRIP THICKNESS AS DETERMINED BYSAID GAUGING MEANS TO PROVIDE A FIRST AND A THIRD INDEXED LENGTH FORLAMINATION SECTIONS OF A SUCCEEDING LAMINATION LAYER THAT DIFFERS FROMTHE FIRST AND THIRD LENGTHS OF THE LAMINATION SECTION OF A PRECEDINGLAMINATION LAYER ESSENTIALLY ONE INCREMENT PROPORTIONAL TO THE STRIPTHICKNESS, AND TO PROVIDE A SECOND INDEXED LENGTH FOR LAMINATIONSECTIONS OF THE SUCCEEDING LAMINATION LAYER THAT DIFFERS FROM THE SECONDLENGTH OF THE LAMINATION SECTION OF A PRECEDING LAMINATION LAYER BYESSENTIALLY TWO INCREMENTS THEREBY TO PROGRESSIVELY PROVIDE THE INDEXEDLENGTHS FOR EACH SUCCESSIVE LAYER BY ALTERATION OF SAID LENGTHS BY SAIDRESPECTIVE INCREMENTS BETWEEN THE FORMATION OF EACH SUCCESSIVELAMINATION LAYER, FORMING MEANS FOR BENDING SAID STRIP MATERIAL AT SAIDFIRST AND SECOND INDEXED LENGTHS, AND MEANS FOR SHEARING AID STRIPMATERIAL AT THE THIRD INDEXED LENGTH TO CUT OFF SAID LAMINATIONSECTIONS.